METHOD FOR FORMING POLY-METAL GATE STACK TO OBTAIN FINE GATE CRITICAL DIMENSION USING TWO-STEP ETCHING PROCESSES

摘要

PURPOSE: A method for forming a poly-metal gate stack is provided to obtain fine gate CD(Critical Dimension) and vertical profile by using two-step etching processes. CONSTITUTION: A gate insulating layer is formed on a semiconductor substrate. A gate stack including a polysilicon layer and a metal film is formed on the gate insulating layer. The metal film and the polysilicon layer are firstly etched in the half thickness of the layer, thereby forming bowing profile. A nitride layer is formed on the resultant structure. The nitride layer and the remaining polysilicon are secondly etched to control DICD(Develop Inspection Critical Dimension).